WO2001056464A1

WO2001056464A1 - Waveguide adapted for use in diagnostic catheters

Info

Publication number: WO2001056464A1
Application number: PCT/US2001/003470
Authority: WO
Inventors: Robert C. Uleski
Original assignee: Fluorrx, Inc.
Priority date: 2000-02-03
Filing date: 2001-02-03
Publication date: 2001-08-09

Abstract

A diagnostic device includes an optical sensor (5) and an optical waveguide (4) held in position with respect to each other by a support member, which may be a catheter wall (3), such that the sensor can be contacted by a medium that may contain analytes. Excitation is directed from the waveguide to the sensor and emissions from the sensor are collected by the waveguide at an angle to its longitudinal axis.

Description

Waveguide Adapted For Use In Diagnostic Catheters

Background

Field of the Invention

The present invention relates generally to detecting analytes using optical sensors and more particularly to the use of optical sensors with waveguides and probes, including catheters, to detect the presence or concentration of analytes of medical interest in body fluids or to detect the presence or concentration of analytes of environmental or safety interest in water or air or to detect the presence or concentration of analytes in manufacturing processes.

Prior Art The use of catheters to introduce nourishment or medicines into patients or to remove samples from a patient is not new. The use of waveguides to introduce electromagnetic radiation into patients and to collect and retrieve resulting fluorescence, reflectance or scattering is also known. Waveguides having sensors that respond optically to the presence or amount of an analyte attached to distal ends are known. Probes based on waveguides that manipulate exiting light by internal reflection for use alone or wit small insertion needles to illuminate sensor films on t e distal end or to illuminate nearby tissue are described.

There remains a need for a medical catheter that also provides information about the presence or concentration of analytes in blood, urine or other body fluids in the vicinity of the catheter while it is in place in the patient.

It is an object of the present invention to fill this need by providing a catheter including an optical sensor to detect and report the presence or concentration of selected analytes in blood.

Summary of the Invention

This and other objects are achieved by an analytical device comprising a catheter capable of supporting an optical sensor in contact with body fluid and also supporting an optical waveguide that is adapted to direct exciting radiation to the sensor, to collect resulting emissions from the sensor, or both wherein the distal end of the waveguide is shaped to direct radiation by refraction to the sensor and to collect emissions from the sensor also by refraction at an angle to the longitudinal axis of the waveguide.

Any catheter in common medical use can be adapted for use in this invention. Arterial and venous catheters are well known. Also, special catheters having a plurality of lumens can be constructed for use in this invention wherein one lumen can be used for removing samples from the patient and/or for introducing materials into the patient while at least one additional lumen supports one or more optical waveguide.

The waveguide or waveguides are connected at the proximal end to a source of excitation for the sensor and at the distal end are held in operative proximity to a sensor. Waveguides useful in this invention are readily commercially available, and any optical waveguide capable of carrying excitation to the sensor can be employed. The same waveguide or different one can be used to carry emissions from the sensor to a spectrophotometer, or other device for analyzing the excitation, at or near the distal end of the catheter for interpretation.

Optical sensors held in contact with body fluid by the catheter and interrogated by excitation from the optical waveguide may be adapted for sensing any analyte in the body fluid, especially those useful in medicine. Typical of such analytes are blood gasses, electrolytes, glucose, heart damage markers PSA and the like. Such sensors are generally known and usually comprise a dye or dyes held in a matrix permeable to the analyte. The dye or dyes signal the presence or amount of an analyte by changing their response to the excitation. Often the dyes are fluorescent in response to the excitation, and the analyte either intensifies or quenches fluorescence, which is monitored.

Characteristics of fluorescence such as intensity, wavelength and lifetime can be monitored by well known techniques.

Brief Description Of The Drawing The is described below in greater detail with reference to the drawing in which: Fig. 1 shows in enlarged and elevated cross section the distal end of a diagnostic device employing the invention.

Detailed Description Fig. 1 shows artery 1 in which has been inserted diagnostic device 2 comprising catheter 3, optical fiber 4 and sensor 5. Sensor 5, and the distal end 6 of optical fiber 4 are held generally stable with respect to each other across space 7 by the wall of catheter 3 in which optical fiber 4 is positioned. Sensor 5 can include any material that produces an optical signal in response to the proximity of an analyte. Normally, sensor 5 will include a matrix that is selective permeable to the analyte. The signal-producing material is normally dispersed in the matrix, and is often a fluorescent dye. Sensor 5 may be supported on an optically transparent layer or may be positioned in an opening in the wall of catheter 3 in the form of a plug.

In operation, excitation light will propagate along optical fiber 4 from a source, not shown, to distal end 6 where it is directed by refraction to sensor 5. Redirection of the exciting radiation from the longitudinal axis of optical fiber 4 is accomplished by a combination of the shape of the fiber at distal end 6 and the ratio of the refractive indices of refraction of the material of optical fiber 4 and the air or other material in the space 7 between distal end 6 and sensor 5.

There may be more than one waveguide corresponding to additional sensors so that a plurality of assays may be accomplished by diagnostic device 2. The additional waveguides may be embedded or held in the walls of catheter 3 or grouped together in at least one additional lumen, not shown, ending in one or more additional sensors.

Distal end 6 of waveguide 4 can be shaped in any way that is not orthogonal to the linear axis of waveguide 4 in order to work with the air or other material in its vicinity to redirect the excitation. Rat cuts ranging from 30 to 60 degrees from the linear axis of waveguides ranging from 250 to 1,000 microns in diameter have been found to be useful in redirecting the excitation and in collecting emissions from a nearby sensor. Such redirection of the excitation and of the collection of the emission from Sensor 5 avoids the necessity for sharp bends in optical guide 4 that would interfere with propagation. It also avoids the need for placing sensor 5 at the bottom of a well or depression having the same depth as waveguide 4 (in order to avoid sharp bends in the waveguide) where debris from the test medium could accumulate and interfere with the assay. It further avoids the use of a thick sensor 5 , that could fill the well or depression down to the depth of the waveguide while preventing accumulation of debris at the surface, but which is known to slow results. With this invention, sensor 5 may be relatively thin and effectively a part of the surface of catheter 3.

It will be understood that sensor 5 can be at any location along the wall of catheter 3. In some applications, not shown, it will be desirable for sensor 5 to be on the inside wall of catheter 3 to assay blood or other body fluid being withdrawn from a patient.

The invention is equally useful in veins, bladders and in the gastrointestinal tract where medically useful assay results are desirable. The invention can also take the form of a probe, similar to one wall of catheter 3, where analyte information is sought but movement of materials into or out of the patient is not necessary. The invention can be used to assay for analytes of environmental interest or of safety concern and is especially when the test medium is remote from the source of excitation or from the spectrophotometer, such as in manufacturing processes, mines and bodies of water.

Other applications and embodiments of this invention will come to mind for those skilled in the art, and such applications and embodiments are intended to be within the scope of the appended claims.

Claims

Claims:

1. A diagnostic system comprising: a. at least one sensor that produces an optically detectable signal in response to excitation, said signal being indicative of the presence or concentration of an analyte in a test medium in contact with the sensor; b. at least one optical fiber adapted at its distal end for delivering excitation to the material from a source thereof or for delivering resulting emissions from the sensor to a detector, or both; and c. a support member for positioning the at least one sensor in contact with the test medium and for holding the at least one sensor and the distal end of the at least one optical fiber in a spaced relationship; wherein the at least one optical fiber is shaped at its distal end so as to direct by refraction excitation to and to collect by refraction resulting emission from the at least one sensor at an angle from the longitudinal axis of the at least one optical fiber and wherein the resulting emission is used to provide information about the presence or concentration of an analyte or of multiple analytes in the test medium.

2. The system of claim 1 wherein the support member is a catheter.

3. The system of claim 2 wherein the at least one sensor is presented to the test medium substantially contiguously with the inner or outer surface of the catheter wall or both.

4. The system of claim 2 wherein the at least one optical fiber is embedded in the catheter wall or is held in a lumen, or both.

5. The system of claim 1 wherein the test medium is a body fluid.

6. The system of claim 1 wherein the sensor produces a fluorescent emission.

7. The system of claim 5 wherein the fluorescent lifetime of the emission is used.

8. The system of claim 1 wherein the test medium is of environmental or safety interest.